Waveguides for Mixed Reality: Principles and Applications

Level: Intermediate Length: 4 hours Format: In-Person Lecture Intended Audience: This course has been prepared for university or industry researchers working with Mixed Reality hardware. It is also helpful to team leaders managing an MR hardware team and human vision researchers who want to understand the capabilities and limitations of the technology. The course assumes the attendees have a first degree in Physics, Engineering, Maths or related subjects and basic optics and vector geometry knowledge. Description: The future Mixed Reality headset will undoubtedly use waveguides to achieve a spectacle form factor and, if required, optical see-through. Mixed Reality waveguides were unheard of ten years ago, but now they receive billions of dollars in investment. Therefore, while there is a plethora of marketing information online, there is limited information on their theory of operation. This course presents the operating principles of diffractive and reflective waveguides and gives examples of their use in existing MR products. The gratings theory is described for diffractive waveguides, emphasizing the k-space representation. The different grating technologies are then presented, including Volume Bragg Gratings (VBGs), Surface Relief Gratings (SRGs), and Polarization Gratings. Reflective waveguides are described, including their manufacturing methods, advantages over diffractive waveguides, and shortcomings. Finally, the operation of a few existing waveguide-based headsets is described. Learning Outcomes: This course will enable you to: - describe how a waveguide is used to make an HMD, differentiate between its function as a combiner and an exit pupil expander and explain the purpose of the display engine - list the different kinds of waveguides - describe in k-space, how the rays propagate from the display engine to the user’s eye - describe the Bragg condition and how it is applied in thin and thick holograms. - compute the diffraction angle (and efficiency) from a volume Bragg grating - describe the basic principle of RCWA - describe and analyze the light path in space in a waveguide-based HMD - describe the basic operation of some existing waveguide-based AR displays Instructor(s): Andreas Georgiou Andreas Georgiou is an Independent Consultant with Reality Optics Ltd, with a particular interest in computational problems in optics. He worked in diffractive optics for over two decades and over a decade in Mixed Reality optics. Andreas enjoys making new ideas into operating prototypes by combining physics, mathematics, engineering, and software. He particularly enjoys working with head-mounted displays, three-dimensional displays, sensors, and everything odd with lenses and gratings inside. Before his current position, he worked with many product groups at Microsoft (Surface, HoloLens, Azure and Kinect), developed micro-confocal endoscopes for surgery, designed space instruments for Mars, and created the first genuinely holographic display. He obtained his PhD in Optics from the University of Cambridge and is also an Engineering Research Fellow at Robinson College, Cambridge. He has over 30 patents and over 20 peer-reviewed publications on head-mounted displays, data storage, holographic displays, and data transmission. Event: SPIE AR | VR | MR 2025 Course Held: 27 January 2025